Goodwill and Intangible Assets Goodwill and Intangible Assets - Weighted Average Life of Intangible Assets (Details)	9 Months Ended
	Sep. 30, 2017
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life of Intangible Assets	5 years 1 month 24 days
Leasehold benefits
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life of Intangible Assets	1 year 8 months 1 day
Developed technologies
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life of Intangible Assets	3 years 9 months 7 days
Non-compete agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life of Intangible Assets	1 year 11 months 5 days
Trade names and trademarks (Finite lived)
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life of Intangible Assets	5 years 2 months 23 days